Abstract

Bingeing on sugar may activate neural pathways in a manner similar to taking drugs of abuse, resulting in related signs of dependence. The present experiments test whether rats that have been bingeing on sucrose and then fasted demonstrate signs of opiate-like withdrawal. Rats were maintained on 12-h deprivation followed by 12-h access to a 10% sucrose solution and chow for 28 days, then fasted for 36 h. These animals spent less time on the exposed arm of an elevated plus-maze compared with a similarly deprived ad libitum chow group, suggesting anxiety. Microdialysis revealed a concomitant increase in extracellular acetylcholine and decrease in dopamine release in the nucleus accumbens shell. These results did not appear to be due to hypoglycemia. The findings suggest that a diet of bingeing on sucrose and chow followed by fasting creates a state that involves anxiety and altered accumbens dopamine and acetylcholine balance. This is similar to the effects of naloxone, suggesting opiate-like withdrawal. This may be a factor in some eating disorders.

Sugar and chow intake during the 28-day access period. A) Rats with intermittent sugar + chow escalated their total daily sugar intake over time. B) Rats with intermittent sugar + chow ate fewer grams of chow than the intermittent chow and ad libitum chow control groups; however, C) there was no difference between groups in total daily caloric intake.

Percent of time spent on the open arm of the elevated plus-maze. Rats that had been previously fed intermittent sugar + chow spent significantly less time on the open arm following 36 h of fasting compared with an equally deprived ad libitum chow group. This suggests anxiety. * = p < 0.05.

Extracellular DA and ACh in the NAc following 24 and 36 h of fasting. A) After 36 h of fasting, DA release in the intermittent sugar + chow group (black bar) was significantly less than both the intermittent chow (grey bar) and ad libitum chow (white bar) control groups. B) Extracellular ACh was significantly increased in the intermittent sugar + chow group at the 36 h fasting point compared with both control groups. * = p < 0.05 compared with both intermittent chow and ad libitum chow.